Long Term Capital Gain Tax

Hi
I have two residential properties in my name..one was gifted to me by mother through a gift deed in 2003. The other was purchased by me in 2010. If I now sell the gifted property do I have to pay LTCGT. Am I eligible for tax exemption if I reinvest in another property. If yes under which section and what are the provisions and conditions.

I own three houses, one of them being bought 3 months back. And i am planning to sell 1 house from the three. Can I claim LTCG exemption. And should I invest within 1 / 2 years to buy from the sale proceeds.